You have top choose an email depending on what email acct you have as example iCoud or gmail and if you have an archive folder or just trash folder. Until you hit the edit button top right for the acct and select one by tapping on it, As soon as you see a blue dot next to the email on the left the trash can will appear bottom left.
It has always been that way. Send yourself a test email and try what i just told you and see if you don't notice as I explained.

If any different get back and let me know and I will tell you what to do.